From: Jason Wang jasowang@redhat.com
[ Upstream commit d71ebe8114b4bf622804b810f5e274069060a174 ]
Commit a7766ef18b33("virtio_net: disable cb aggressively") enables virtqueue callback via the following statement:
do { if (use_napi) virtqueue_disable_cb(sq->vq);
free_old_xmit_skbs(sq, false);
} while (use_napi && kick && unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
When NAPI is used and kick is false, the callback won't be enabled here. And when the virtqueue is about to be full, the tx will be disabled, but we still don't enable tx interrupt which will cause a TX hang. This could be observed when using pktgen with burst enabled.
TO be consistent with the logic that tries to disable cb only for NAPI, fixing this by trying to enable delayed callback only when NAPI is enabled when the queue is about to be full.
Fixes: a7766ef18b33 ("virtio_net: disable cb aggressively") Signed-off-by: Jason Wang jasowang@redhat.com Tested-by: Laurent Vivier lvivier@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/virtio_net.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 48fb7bdc0f0b..9222be208aba 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1780,8 +1780,10 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) */ if (sq->vq->num_free < 2+MAX_SKB_FRAGS) { netif_stop_subqueue(dev, qnum); - if (!use_napi && - unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { + if (use_napi) { + if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) + virtqueue_napi_schedule(&sq->napi, sq->vq); + } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { /* More just got used, free them then recheck. */ free_old_xmit_skbs(sq, false); if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {